1. Technical Field
The present invention relates to a driver circuit for a voltage-controlled switching element.
2. Related Art
JP-A-2008-249642 discloses a detection circuit having an electrical configuration that includes a potential supply unit, an internal circuit, and a supply path. The potential supply unit outputs a predetermined potential obtained by a potential of an external power source and ground potential being divided by a resistor element. The internal circuit is an integrated circuit or the like. The supply path connects the potential supply unit and the internal circuit. In this electrical configuration, the detection circuit detects an open circuit state between the potential supplying unit and the supply path.
When the open circuit state occurs, the potential at the connection point between the supply path and the internal circuit differs from the potential when the potential supply unit and the supply path are connected normally. Therefore, the detection circuit compares the potential at the connection point (potential detection position) between the supply path and the internal circuit with a predetermined reference potential. Thus, the detection circuit detects the open circuit state between the potential supply unit and the supply path.
A driver circuit for a voltage-controlled switching element is known in related art. This driver circuit is connected to a control terminal of the voltage-controlled switching element via a connection line. In this configuration, an open circuit state between the control terminal and the connection line is required to be detected. Here, application of the detection circuit described in JP-A-2008-249642 may be considered. However, even when the detection circuit described in JP-A-2008-249642 is applied, the open circuit state between the control terminal and the potential detection position on the connection line cannot be detected. In particular, a state in which the connection line is not connected to the control terminal cannot be detected.
At present, the open circuit state between the control terminal of the voltage-controlled switching element and the connection line, or in other words, the open circuit state between the control terminal and the driver circuit is detected based on a detection value from a current sensor. The detection value is obtained by a current that is sent to the switching element. Therefore, a problem occurs in that, unless the current is sent to the switching element, the open circuit state between the control terminal and the driver circuit cannot be detected.